Japanese scientists compared the drinking habits of 63,232 cancer patients in Japan with those of an equal number of healthy controls. All reported their average daily alcohol intake and the number of years they had been drinking.
After controlling for smoking, hypertension, diabetes, obesity and other characteristics, they found that drinking the equivalent of six ounces of wine, 17 ounces of beer or two ounces of whiskey a day for 10 years increased the relative risk of cancer by 5 percent. After two drinks a day for 40 years, the relative risk of having any cancer increased by 54 percent compared with a nondrinker. The associations were particularly strong for cancers of the mouth, throat, stomach and colon.
The study, in the journal Cancer, has certain limitations. The drinking history data was collected by self-reports, which can be unreliable, and the researchers were unable to control for family history of cancer, diet or physical activity. In addition, the Japanese have a higher prevalence of genetic variations that make them slower at metabolizing alcohol, and the results may not be generalizable to other populations.
“One drink a day is probably not a big problem,” said the lead author, Dr. Masayoshi Zaitsu of the University of Tokyo. “But drinking too much over long periods of time might be dangerous. We enjoy drinking, but we need to think about it.”